WEBVTT 1 00:00.000 --> 00:04.160 All right, so let's go ahead and log in into the lab 2 00:04.160 --> 00:06.600 and actually configure weighted random early detect. 3 00:06.600 --> 00:08.800 Now what we're gonna find is if we just enable 4 00:08.800 --> 00:10.120 weighted random early detect, 5 00:10.120 --> 00:14.280 it's actually going to base it on IP precedence, not DSCP. 6 00:14.280 --> 00:17.320 And Cisco actually has a bunch of default values 7 00:17.320 --> 00:19.400 in place for IP precedence, 8 00:19.400 --> 00:22.800 because there's only eight different tags in IP precedence. 9 00:22.800 --> 00:25.960 Well, when we enable DSCP based weighted random early detect, 10 00:25.960 --> 00:28.880 which is what we should do in real life situations, 11 00:28.880 --> 00:30.140 then we're gonna find that, well, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 11 00:28.880 --> 00:30.140 then we're gonna find that, well, 12 00:30.140 --> 00:31.960 Cisco's not going to put a bunch of defaults 13 00:31.960 --> 00:34.160 for all of the different possible tags. 14 00:34.160 --> 00:37.560 And so now it is more up to us to create those. 15 00:37.560 --> 00:40.320 But interestingly, IP precedence values 16 00:40.320 --> 00:43.120 can give us a decent template to work off of. 17 00:43.120 --> 00:45.880 So let's go ahead and see this in action. 18 00:45.880 --> 00:48.880 What we're gonna do here is we're just going to 19 00:48.880 --> 00:52.520 do some example red configurations by creating, 20 00:52.520 --> 00:54.840 first of all, a class map. 21 00:54.840 --> 00:57.560 So we're gonna do that match any concept for, 22 00:57.560 --> 00:59.520 we'll do AF2X here, 23 00:59.520 --> 01:03.980 and I'm gonna say match DSCP and list out all of those. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 23 00:59.520 --> 01:03.980 and I'm gonna say match DSCP and list out all of those. 24 01:03.980 --> 01:10.440 And from here, we're going to get onto that policy map test. 25 01:10.440 --> 01:12.360 And now I'm gonna configure that class. 26 01:12.360 --> 01:14.560 So class AF2X. 27 01:14.560 --> 01:18.900 And now I can enable random detect. 28 01:18.900 --> 01:22.760 Now, oh, yeah, let's get a bandwidth command in there. 29 01:22.760 --> 01:24.480 So that is going to be required. 30 01:24.480 --> 01:26.840 I'm just gonna say bandwidth 10,000 31 01:26.840 --> 01:28.760 and now enable random detect. 32 01:28.760 --> 01:32.320 So now what we can do is apply this to an interface. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 32 01:28.760 --> 01:32.320 So now what we can do is apply this to an interface. 33 01:32.320 --> 01:35.200 So let's get on interface gig one zero 34 01:35.200 --> 01:38.600 and do that service policy command to apply it 35 01:38.600 --> 01:41.020 and we'll do it in the outbound direction. 36 01:41.020 --> 01:45.360 And then remember that amazing command 37 01:45.360 --> 01:48.480 show policy map interface 38 01:48.480 --> 01:50.120 that we talked about in the last skill. 39 01:50.120 --> 01:52.560 This is a really good command 40 01:52.560 --> 01:55.100 for weighted random early detect as well. 41 01:55.100 --> 01:58.340 So here's our class AF2X. 42 01:58.340 --> 02:00.980 We see the traffic that's coming into, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 42 01:58.340 --> 02:00.980 We see the traffic that's coming into, 43 02:00.980 --> 02:02.600 into and out of it, et cetera, 44 02:02.600 --> 02:04.060 depending on the direction. 45 02:04.060 --> 02:06.400 But right away we see what happened here. 46 02:06.400 --> 02:09.180 We configured weighted random early detect, 47 02:09.180 --> 02:12.140 but we configured it with just the default settings, 48 02:12.140 --> 02:16.300 which means we actually have enabled it for IP presidents. 49 02:16.300 --> 02:18.400 Not ideal in a real world situation, 50 02:18.400 --> 02:21.140 but what this allows us to do is see 51 02:21.140 --> 02:22.760 how exactly it's configured. 52 02:22.760 --> 02:25.500 So we can see some statistics here, which is cool. 53 02:25.500 --> 02:30.060 But over here we see that Cisco with a class IP president zero WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 53 02:25.500 --> 02:30.060 But over here we see that Cisco with a class IP president zero 54 02:30.060 --> 02:33.080 sets the minimum threshold to 20 and the maximum to 40. 55 02:33.080 --> 02:36.500 All of these are set to a maximum of 40 you'll notice. 56 02:36.500 --> 02:40.580 And then the mark probability is set to one out of 10. 57 02:40.580 --> 02:43.420 Now again, it's not the mark probability denominator 58 02:43.420 --> 02:45.780 because the denominator is itself 10. 59 02:45.780 --> 02:47.780 And we'll see how we configure that here in a moment, 60 02:47.780 --> 02:50.280 but when we configure the denominator to be 10, 61 02:50.280 --> 02:53.060 that makes it so that the mark probability itself 62 02:53.060 --> 02:55.940 is one out of 10 or 10%. 63 02:55.940 --> 02:59.540 So this percentage is what we grow to. 64 02:59.540 --> 03:04.620 So for class zero, starting at an average cube size of 20 WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 64 02:59.540 --> 03:04.620 So for class zero, starting at an average cube size of 20 65 03:04.620 --> 03:08.420 packets, it's going to grow linearly all the way up 66 03:08.420 --> 03:12.220 to a 10% drop probability before we start tail dropping 67 03:12.220 --> 03:13.460 everything. 68 03:13.460 --> 03:16.540 Now putting everything at 40 here is usually not 69 03:16.540 --> 03:18.380 a great idea. 70 03:18.380 --> 03:21.960 And so I wouldn't necessarily take these as Cisco recommendations, 71 03:21.960 --> 03:25.320 but it's kind of interesting to see where they start to drop 72 03:25.320 --> 03:25.840 packets. 73 03:25.840 --> 03:29.200 And we do see that something as important as an IP 74 03:29.200 --> 03:33.320 president of seven is going to start getting dropped at 34. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 74 03:29.200 --> 03:33.320 president of seven is going to start getting dropped at 34. 75 03:33.320 --> 03:34.720 So let's start to change this. 76 03:34.720 --> 03:36.360 We're going to switch it over to DSCP. 77 03:36.360 --> 03:42.160 I'm going to get back onto my policy map, get into that class AF2X. 78 03:42.160 --> 03:46.160 Whoops, we've got to do DSCP. 79 03:46.160 --> 03:46.840 Did I do that right? 80 03:46.840 --> 03:47.120 Nope. 81 03:47.120 --> 03:48.320 I didn't add the DSCP. 82 03:48.320 --> 03:49.040 That's funny. 83 03:49.040 --> 03:51.760 OK, so it is just AF2X. 84 03:51.760 --> 03:53.240 Perfect. 85 03:53.240 --> 03:54.680 So we're back onto this. 86 03:54.680 --> 03:57.520 I'm going to say no random detect, 87 03:57.520 --> 04:01.200 because I have to disable IP precedence based random detect. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 87 03:57.520 --> 04:01.200 because I have to disable IP precedence based random detect. 88 04:01.200 --> 04:05.280 And now I'm going to say random detect question mark. 89 04:05.280 --> 04:09.320 And we're going to see that I can add this DSCP based concept. 90 04:09.320 --> 04:11.800 Now, precedence based is an option here, 91 04:11.800 --> 04:13.280 but it's the default option. 92 04:13.280 --> 04:17.560 So this is why we need to specify DSCP based. 93 04:17.560 --> 04:22.960 And now I can start to look at my red configurations, 94 04:22.960 --> 04:24.680 w red configurations. 95 04:24.680 --> 04:28.360 Now, again, what if I just take a moment to say show policy map 96 04:28.360 --> 04:30.240 interface gig 1, 0? WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 96 04:28.360 --> 04:30.240 interface gig 1, 0? 97 04:30.240 --> 04:32.480 This is still applied to the interface. 98 04:32.480 --> 04:35.200 So here's my AF2X class. 99 04:35.200 --> 04:39.400 And notice we don't actually have any weighted random early 100 04:39.400 --> 04:42.680 detect configuration in place for DSCP. 101 04:42.680 --> 04:45.800 There is no defaults for DSCP. 102 04:45.800 --> 04:49.440 So that's something to keep in mind there. 103 04:49.440 --> 04:52.360 But fortunately, we can configure it ourselves. 104 04:52.360 --> 04:58.720 So what we're going to do is we're going to say random detect. 105 04:58.720 --> 05:01.920 And then DSCP, I'm going to specify my tag here. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 105 04:58.720 --> 05:01.920 And then DSCP, I'm going to specify my tag here. 106 05:01.920 --> 05:04.760 So I can specify whichever tag we're going to put in here. 107 05:04.760 --> 05:08.160 This is the 2xq I'm going to start with 23. 108 05:08.160 --> 05:12.760 This is my higher percent chance traffic of dropping. 109 05:12.760 --> 05:17.280 So we probably want a little bit lower threshold to start with. 110 05:17.280 --> 05:21.200 So again, I can set my minimum threshold in packet count. 111 05:21.200 --> 05:23.240 Amazing how many packets we can put in a queue. 112 05:23.240 --> 05:27.120 That's at least according to Cisco range there. 113 05:27.120 --> 05:31.040 But I'm just going to say, out of 40, I'm going to say 28 here. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 113 05:27.120 --> 05:31.040 But I'm just going to say, out of 40, I'm going to say 28 here. 114 05:31.040 --> 05:34.440 And then maybe a max range of 34. 115 05:34.440 --> 05:37.400 And then this is where I set my mark probability denominator. 116 05:37.400 --> 05:40.200 So again, I'm not saying 1 out of 10, 117 05:40.200 --> 05:41.640 because that'd be the mark probability. 118 05:41.640 --> 05:44.560 I'm just specifying the denominator of 10. 119 05:44.560 --> 05:47.800 So now let's go back and look at that interface configuration. 120 05:47.800 --> 05:52.200 And we see that we have AF23 with a minimum threshold of 28, 121 05:52.200 --> 05:56.560 max of 34, mark probability of 110. 122 05:56.560 --> 06:00.040 So now I can do something similar here. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 122 05:56.560 --> 06:00.040 So now I can do something similar here. 123 06:00.040 --> 06:02.840 Random detect DSCP AF22. 124 06:02.840 --> 06:05.880 Let's make it a little bit higher, not 28, but 30. 125 06:05.880 --> 06:08.560 And not 34, but 36. 126 06:08.560 --> 06:11.360 And we can set a mark probability of 25 here. 127 06:11.360 --> 06:14.160 We don't have to use the same slope. 128 06:14.160 --> 06:17.680 So now if I look at this, we'll see 129 06:17.680 --> 06:21.680 we've got AF23 at the original one that we configured. 130 06:21.680 --> 06:26.080 But now AF22 starts at 30 and to 36 and has a-- 131 06:26.080 --> 06:28.520 I said 25, 1 out of 25. 132 06:28.520 --> 06:31.320 Yeah, I meant to say 1 out of 4, so that was 25%. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 132 06:28.520 --> 06:31.320 Yeah, I meant to say 1 out of 4, so that was 25%. 133 06:31.320 --> 06:33.440 But keep that in mind. 134 06:33.440 --> 06:36.320 Maybe we should practice this a little bit, 135 06:36.320 --> 06:37.680 make sure we've got everything down. 136 06:37.680 --> 06:38.760 All right, there we go. 137 06:38.760 --> 06:40.680 So I wanted it to be 25%. 138 06:40.680 --> 06:43.480 That would be a mark probability of 1/4. 139 06:43.480 --> 06:48.600 And lastly, our AF21 traffic should be even higher. 140 06:48.600 --> 06:53.560 So minimum threshold 32, maximum threshold 38. 141 06:53.560 --> 06:57.040 And then we can say maybe when I actually 142 06:57.040 --> 07:00.040 make it a much lower slope. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 142 06:57.040 --> 07:00.040 make it a much lower slope. 143 07:00.040 --> 07:06.120 So rather than 4 or 10, I could do something like 20. 144 07:06.120 --> 07:07.720 So that's like a 5%. 145 07:07.720 --> 07:11.880 1 and 20 is 5% at the most before it starts dropping fully. 146 07:11.880 --> 07:15.400 And so there we go. 147 07:15.400 --> 07:17.360 There's our configuration in place. 148 07:17.360 --> 07:19.480 And say, well, why wouldn't we specify this at 40? 149 07:19.480 --> 07:19.960 We could. 150 07:19.960 --> 07:22.440 We could say at 40 would start dropping traffic. 151 07:22.440 --> 07:28.560 Just keep in mind that there is potentially value in putting 152 07:28.560 --> 07:28.960 it lower. 153 07:28.960 --> 07:30.680 Usually we would just say 40. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 153 07:28.960 --> 07:30.680 Usually we would just say 40. 154 07:30.680 --> 07:33.720 I'm not sure why I did 38 there. 155 07:33.720 --> 07:34.920 Now let's just put it at 40. 156 07:34.920 --> 07:35.720 There we go. 157 07:35.720 --> 07:37.600 We really shouldn't drop the highest priority packets 158 07:37.600 --> 07:40.520 until the queue is full. 159 07:40.520 --> 07:43.720 But either way, we do see that this 160 07:43.720 --> 07:47.920 is going to allow us to configure that weighted random early 161 07:47.920 --> 07:51.840 detect in a way that takes a look at the different tags, 162 07:51.840 --> 07:56.880 drops them in the proper order at the proper rates 163 07:56.880 --> 07:59.560 that we very intentionally configure. 164 07:59.560 --> 08:02.400 And we can confirm the configuration with that awesome WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 164 07:59.560 --> 08:02.400 And we can confirm the configuration with that awesome 165 08:02.400 --> 08:05.640 command show policy map interface to see and make sure 166 08:05.640 --> 08:08.600 that our configuration is correct.